Fire retardant compositions are generally applied to fire unstable materials as a surface coating. The composition, in a liquid form, is applied to the surface by brush painting, or spray painting or by some form of printing equipment, such as the use of a doctor roll. If the liquid is a viscous relatively thick material, its effectiveness will depend on its ability to adhere to and remain on the surface of the fire unstable material during production, handling, installing and use of the resultant fire retardant structure. Upon exposure to flame and heat, it may separate from the surface or the action of the flame and heat to the fire unstable material and defeating the purpose of applying the fire retardant material.
When the fire retardant material is relatively inert, or has an inert surface finish as in the case of polymeric materials or a particle board bonded with a resinous type material, such as, phenol-formaldehyde resin, it is difficult to get good adherence of the fire retardant composition.
The use of additional substances in an attempt to increase adherence may be self-defeating. Adhesives, solvents, etc. may offset or detract from the effectiveness of the fire retardant material. These substances may be flammable themselves or may react with the fire retardant composition in some fashion to lessen its usefulness.
The present invention has as a principal object the incorporation of intumescent fire retardant compositions into the surface of fire unstable materials so that they will tenaciously adhere and remain as a part of the fire unstable material during production, handling and use of the resulting fire retardant structure. It has also been discovered that by the present invention the resistance to flame and heat exposure of the resultant structure are significantly enhanced.